Alkenyl aromatic resinous packaging



Dec. 20, 1966 E. PFISTER 3,293,047

ALKENYL AROMATIC RESINOUS PACKAGING Filed June 20, 1963 INVENTOR. R0406 5. P/As/er United States Patent 3,293,047 ALKENYL AROMATIC RESINOUS PACKAGING Ralph E. Pfister, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed June 20, 1963, Ser. No. 289,257 6 Claims. (Cl. 99-171) This invention relates to an improved alkenyl aromatic resinous package. It more particularly relates to improved packages comprising rigid alkenyl aromatic resinous containers having interrupted or multiple thread closures.

By the term alkenyl aromatic resin is meant a solid polymer of one or more polymerizable alkenyl aromatic compounds. The polymer or copolymer comprises, in chemically combined form, at least 50 percent by weight of at least one alkenyl aromatic compound having the general formula:

wherein Ar represents an aromatic hydrocarbon radical or an aromatic halohydrocarbon radical of the benzene series, and R is hydrogen or the methyl radical. EX- amples of such alkenyl aromatic resins are the solid homopolymers of styrene, a-methylstyrene, ortho-methylstyrene, meta-methylstyrene, para-methylstyrene, Ar-ethylstyrene, Ar-vinylxylene, Ar-chlorostyrene, or Ar-bromostyrene; the solid copolymers of two or more of such alkenyl aromatic compounds with minor amounts of other readily polymerizable olefinic compounds such as divinylbenzene, methylmethacrylate, or acrylonitrile, etc.

Rigid containers prepared from such alkenyl aromatic resins and particularly those prepared from polystyrene which utilize either a multiple thread closure or an interrupted thread closure have not generally been satisfactory for the packaging of many materials including peanut butter, mayonnaise, detergents and the like. Usually such jars or containers comprise a generally cylindrical body closed at one end, opened at the opposite end and having thread portions or lugs adjacent the open end to en gage a suitable screw type cap. Such caps are adapted to be fully engaged or released by a rotation of 90 or less of the cap relative to the container. Such containers, when packed with peanut butter, mayonnaise and like substances, closed by means of a cap prepared from sheet metal or like material and closed with suflicient torque (usually about 35 inch pounds) fractured after a period of only about one and one-half hours.

It is an object of this invention to provide an improved alkenyl aromatic resinous rigid container having .a screw type cap.

It is a further object of this invention to provide an alkenyl aromatic resinous container which does not crack or deteriorate on standing when in engagement with a screw type cap.

A further object of this invention is to provide an improved n'gid alkenyl aromatic resinous rigid container which is suitable for packaging materials such as peanut butter, mayonnaise and the like.

These benefits and other advantages in accordance with the invention are achieved by providing an alkenyl aromatic resinous rigid container having a generally circular opening and a cylindrical configuration adjacent the opening, the outer portion of the cylindrical portion of said container being provided with a plurality of thread portions adapted to engage internally projecting lugs on a mating closure, said thread portions and lugs so constructed and arranged as to permit release of the closure from the container by a relative rotation of up to 90, said 3,293,047 Patented Dec. 20, 1966 thread portions having a lug engaging surface disposed at an angle of up to about 10 as measured from a plane generally parallel to the opening of the container.

Further features and advantages of the invention will become more apparent from the following specification when taken in connection with the drawing wherein:

FIGURE 1 depicts a partly-in-section view of a package in accordance with the present invention;

FIGURE 2 is an enlarged sectional view taken along the line 22 of FIGURE 1;

FIGURE 3 further clarifies the lug arrangement of the container of FIGURE 1.

In FIGURE 1 there is illustrated a package 10 in accordance with the invention comprising a rigid alkenyl aromatic resinous container 12. The container 12 comprises a body portion 13 having .a closed bottom 14 and a generally cylindrical neck portion 15. The cylindrical neck portion 15 defines an opening 17 and a generally cylindrical exterior wall portion 18. Affixed to the cylindrical wall portion 18 are a plurality :of thread portions 20. The thread portions 20 are primarily defined by an upper surface 21 and a ilug engaging surface 22. Dispose-d within the container 12 is a packaged material 23. A screw type cap 24 having a dependent rim portion 25 which in turn supports the thread engaging lugs 27 is in engagement with the neck portion 15 effectively closing the container. The cap 24 is provided with an internal annular gasket 28.

FIGURE 2 depicts an enlarged detailed view of the engagement of the lug 27 with the lug engaging surface 22 of a thread 18. The angle A designates the angular displacement of the lug engaging face 22 from a plane generally normal to the axis of generation of the cylindrical surface 18 of the neck portion 15. The angle A is measured in a generally radially outward direction.

In FIGURE 3 there is illustrated a top view of the container 12 showing the positioning of the thread portions 18 about the periphery of the neck portion 15.

Alkenyl aromatic resinous containers in accordance with the present invention are advantageously prepared by injection molding in a manner well known to the art. If desired, they may be also prepared by blow molding or compression molding. However, for commercial purposes, injection molding is usually preferred. Although numerous alkenyl aromatic resinous materials may be chosen, particularly desirable are the clear, colorless transparent polymers such as polystyrene, and copolymers of styrene including those of styrene with various acrylate monomers such as a copolymer of polystyrene containing 20 percent by weight of methyl acrylate. It is critical that the angular displacement A of the lug engaging face of the thread portions 20 of the container not be greater than about 10. The angular displacement referred to is shown in FIGURE 2 and designated by the letter A. If the angular displacement is greater than about 10 it is found that unsatisfactory containers are produced and they tend to fracture when packed with peanut butter, mayonnaise, detergents and similar materials. The angle A may be positive as shown in FIGURE 2 or negative. However, for convenience in most molding operations easier release from the mold is obtained when the angle is positive. Generally it is preferred that the angle be between about 1 and 6 for most convenient production.

By way of further illustration, a plurality of containers substantially as shown in FIGURE 1 were fabricated by injection molding from polystyrene. Each container had a capacity of 16 ounces liquid measure and an opening of about 82 millimeters in diameter. The container had four threads, each of equal pitch and position adjacent the opening. The angular displacement of the lug engagin-g surfaces of the thread portions was +2. These containers were then filled within about one-half inch from the top, some with peanut butter, some with mayonnaise.

A standard commercially available metal cap having lugsto engage each of the thread portions was placed on the containers and tightened by applying a torque of 50 inch pounds: A similar'group of containers were fabricated utilizing the same batch of polystyrene and identical molding conditions with the exception that the die employed gave a container having the conventional thread known to the art wherein the angular displacement of the lower surface was about 45 Similarly a portion of the containers molded in this manner were filled with peanut butter and another portion with mayonnaise, also to within about one-half inch from the top. The containers were closed using identical caps to those employed with the containers in accordance with the invention and were tightened with a torque of 50 inch pounds. After a period of one and one-half hours the containers in accordance with the pri-orart showed numerous cracks in the walls whereas the containers in accordance with the present invention showed no cracking after 6 weeks. All containers were stored under identical conditions.

Similar beneficial results were achieved when polystyrene containers were prepared having 6 thread portions rather than 4.

In a manner similar to the foregoing illustrations, other alkenyl aromatic resins were utilized with equal benefit including such copolymers as those prepared by the copo lymerization of 10 parts of methyl methacrylate with 90 parts of styrene, parts of acrylonitrile and 85 parts styrene, 40 parts of ethyl acrylate and 60 parts styrene, polytertiarybutylstyrene, and the like.

As is apparent from the foregoing specification, the article of the present invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. For this reason, it is to be fully understood that all of the foregoing is intended to be merely illustrative and is not to be construed or interpreted as being restrictive or otherwise limiting of the present invention, excepting as it is set forth and defined in the hereto appended claims.

What is claimed is:

1. In an alkenyl aromatic resinous rigid container having a generally circular opening, a cylindrical configuration adjacent to said opening, the outer portion of the cylindrical portion of said container being provided with a plurality of thread portions adapted to engage internally projecting lugs on a mating closure, said thread portions and lugs so constructed and arranged so as to permit release of the closure from the container by a relative rotation of up to about the improvement which comprises providing the thread portions with a lug engaging surface disposed at an angle of up to 10 as measured from a plane generally parallel to the opening of the container and in a radially outward direction.

2. The container of claim 1 wherein the alkenyl aromatic resinous material is polystyrene.

3.- The container of claim 1 wherein the lug engaging surfaces are disposed at an angle of between 1 and 6 from a plane generally parallel to the opening of the container and normal to the axis of generation of the cylindrical portion of the container, said angle being measured as displacement toward the opening.

4. The container of claim 1 including a quantity of a foodstuif therein and a mating closure in sealing engagement therewith.

5. The container of claim 4 wherein the container is polystyrene.

6. The container of claim 5 wherein the foodstuff is peanut butter.

References Cited by the Examiner UNITED STATES PATENTS 1,676,023 7/ 1928 Hammer 215-44 1,841,597 1/1932 Hammer 21544 2,403,131 7/1946 Smith 215-44 2,617,553 11/1952 Lay 22039 2,640,626 6/1953 Newell 22040 2,661,966 12/1953 Edelen 2l543 2,876,926 3/ 1959 Gronomeyer 22039 2,950,033 8/1960 Henchert 22039 2,965,256 12/ 1960 Yochem 215-43 2,965,496 12/ 1960 Serdar 99171 3,088,830 5/1963 Graham 99--171 JOSEPH R. LECLAIR, Primary Examiner.

RAYMOND N. JONES, FRANKLIN T. GARRETT,

, Examiners. R. PESHOCK, Assistant Examiner. 

1. IN AN ALKENYL AROMATIC RESINOUS RIGID CONTAINER HAVING A GENERALLY CIRCULAR OPENING, A CYLINDRICAL CONFIGURATION ADJACENT TO SAID OPENING, THE OUTER PORTION OF THE CYLINDRICAL PORTION OF SAID CONTAINER BEING PROVIDED WITH A PLURALITY OF THREAD PORTIONS ADAPTED TO ENGAGE INTERNALLY PROJECTING LUGS ON A MATING CLOSURE, SAID THREAD PORTIONS AND LUGS SO CONSTRUCTED AND ARRANGED SO AS TO PERMIT RELEASE OF THE CLOSURE FROM THE CONTAINER BY A RELATIVE ROTATION OF UP TO ABOUT 90*, THE IMPROVEMENT WHICH COMPRISES PROVIDING THE THREAD PORTIONS WITH A LUG ENGAGING SURFACE DISPOSED AT A ANGLE OF UP TO 10* AS MEASURED FROM A PLANE GENERALLY PARALLEL TO THE OPENING OF THE CONTAINER AND IN A RADIALLY OUTWARD DIRECTION. 